In a tunnel type vehicle wash system, a conveyor may be used to convey a vehicle through various wash stations, such as a pre-soak station, a soap dispenser, a tire washing station, a sprayer station, one or more rotating brushes, a pre-rinse station, a wax applicator station, a rinsing device, and/or a drying station for example. The conveyor may comprise an elongate track flanked by a pair of rails which act as a tire guide. A tire of a vehicle may be pushed along the track, within the tire guide (i.e. between the rails), by a longitudinally advancing roller to cause the vehicle to roll forwardly from the entrance end to the exit end of the conveyor. The roller may be driven by an endless drive, such as a chain or belt.
The endless drive of the conveyor may extend between a sprocket at an exit end of the conveyor and a freely rotating take-up drum at an entrance end of the conveyor. The sprocket and drum are typically situated below a track level of the conveyor. The sprocket may be rotatably driven by an electric motor for example to cause the endless drive to move.
Tensioning of the endless drive may be achieved through a biasing of the take-up drum away from the sprocket. For example, the take-up drum may be mounted onto a take-up drum carriage (or simply “drum carriage”) that is free to slide, on slide rails or shafts, longitudinally with respect to, and in alignment with, the endless drive. The slidable drum carriage may be biased away from the sprocket using biasing means. The biasing means may for example be gas springs, which may have the appearance of shock absorbers.
Should the endless drive slacken, e.g. due lengthening of the drive over its usable lifetime, the gas springs may automatically extend so as to slide the drum carriage away from the sprocket in order to take up the slack. Should the endless drive tighten, e.g. due to sudden increased loading of the forward-moving portion of the endless drive when a roller engages a vehicle tire entering the conveyor, the increased tension on the forward moving-portion of the drive may exceed the biasing force of the gas springs, causing them to compress. In this case, the drum carriage may slide towards the sprocket and thereby reduce the tension on the endless drive to an acceptable level.